Studies are planned on patients with heart failure, dogs with experimental myocardial damage, and animals with induced coronary stenosis. The purpose of the study is to gain insight into the circulatory response to vasodilator drugs in chronic low-output heart failure, to study the role of alterations in systemic vascular resistance on the natural history of myocardial dysfunction and to evaluate the possible role of alterations in proximal coronary vascular resistance on myocardial ischemia as a possible factor in the low cardiac output syndrome in chronic coronary artery disease. BIBLIOGRAPHIC REFERENCES: Franciosa J.A., Cohn J.N.: Hemodynamic improvement with hydralazine in left heart failure. Clin Res 24: 271A, 1976. Schwartz J.S., Carlyle P.F., McGregor L.R., Ponto R., Runge W., Cohn J.N.: Myocardial perfusion imaging with thallium-201 in the pig. Clin Res 24: 240A, 1976.